Arrays yes, structures are not as nice. I think even in the
latest version of AKCL C structures do not map directly to LISP
structures. For arrays, look in the file object.h . To reference
a LISP array in C your routine must get an argument off the
value stack vs_base[???] where ??? is the argument number. There
are several array types so make sure you have the right one. But,
a vector for example, is referenced as x->v.v_self[index].
If you wish to create a vector and return it to LISP it
must be created in the LISP space of your memory. This can be done
by first calling alloc_object and then for an array calling
array_allocself. Here is some psuedocode:
x = alloc_object(t_vector);
x->v.v_self = (object *)NULL;
x->v.v_displaced = Cnil;
x->v.v_dim = vector_length;
x->v.v_adjustable = FALSE;
x->v.v_hasfillp = FALSE;
x->v.v_fillp = x->v.v_dim;
x->v.v_elttype = (short)aet_fix;
vs_push(x); /* protect vector structure from GC */
array_allocself(x,FALSE);
/* before you return from routine to LISP remember to do a vs_pop for every
vs_push so the value stack gets cleaned up properly */
Suggested reading alloc.c, array.c, object.h, bds.h and others as appropriate.
Good Luck.
Paul H